#include "mystdio.h"
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
mFILE *mfopen(const char *filename, const char *mode)
{
    // 封装 system call open打开文件
    int fd = -1;
    if (strcmp(mode, "r") == 0)
    {
        fd = open(filename, O_RDONLY);
    }
    else if (strcmp(mode, "w") == 0)
    {
        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
    }
    else if (strcmp(mode, "a") == 0)
    {
        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
    }
    // fd fail
    if (fd < 0)
        return NULL;
    // file open fail 文件打开失败
    mFILE *mf = (mFILE *)malloc(sizeof(mFILE));
    if (!mf)
    {
        close(fd);
        return NULL;
    }
    // mFILE状态
    mf->fileno = fd;
    mf->flag = FLUSH_LINE;
    mf->cap = SIZE;
    mf->size = 0;

    return mf;
}

//  本质是写到内核缓冲区
void mfflush(mFILE *stream)
{
    if (stream->size > 0)
    {
        // write是将数据写到内核文件的文件缓冲区中
        write(stream->fileno, stream->outbuffer, stream->size);
        // 刷新到外设
        fsync(stream->fileno);
        stream->size = 0;
    }
}

// myfwrite就做拷贝
int mfwrite(const void *ptr, int num, mFILE *stream)
{
    // 1.拷贝
    memcpy(stream->outbuffer + stream->size, ptr, num);
    stream->size += num;
    // 2.检测是否刷新
    if (stream->flag == FLUSH_LINE && stream->size > 0 && stream->outbuffer[stream->size - 1] == '\n')
    {
        mfflush(stream);
    }
    return num;
}

void mfclose(mFILE *stream)
{
    // 检测有效字符个数是否大于0 大于0就刷新
    if (stream->size > 0)
    {
        mfflush(stream);
    }
    // 刷新之后关闭文件
    close(stream->fileno);
}
